Cushioning elements are of great importance in the area of sports apparel and are used in clothing for a large variety of sports. Examples in this case are winter sports apparel, running apparel, outdoor apparel, football apparel, golf apparel, combat sports apparel, or the like. In general, these cushioning elements serve the protection of the wearer from knocks and blows and for padding, for example in the event of the wearer falling. For this, cushioning elements typically contain one or more deformation elements, which deform under external pressure or impact and thus absorb the impact energy.
The cushioning elements play a very important role in the construction of shoes, in particular sports shoes. With the aid of cushioning elements that are arranged as soles or parts of soles, shoes are provided with a range of different characteristics that may be pronounced in various strengths depending on the special type of shoe. Primarily, the shoe soles have a protective function. By way of their increased stiffness in comparison to the shoe upper, they protect the foot of the respective wearer from injury through sharp objects on which the shoe wearer treads. Furthermore, the shoe sole protects the shoe from excessive wear generally by means of an increased abrasion resistance. In addition, shoe soles may increase the grip of a shoe on the respective ground and thus facilitate faster movement. It may be a further function of a shoe sole to provide a certain stability. In addition to this, for example, a shoe sole may act as a cushion in order to cushion the forces that occur when the shoe impacts the ground. Finally, a shoe sole may protect the foot from dirt or water spray and/or provide a number of other functionalities.
In order to satisfy the wealth of functionalities, different materials and manufacturing methods are known in the prior art from which cushioning elements may be made for sports apparel.
As examples, reference is made to cushioning elements that are arranged as shoe soles made out of ethylene vinyl acetate (EVA), thermoplastic polyurethane (TPU), rubber, polypropylene (PP) or polystyrene (PS). Each of these different materials provides a special combination of different characteristics that are more or less well suited for soles of specific shoe types depending on the specific requirements of the respective shoe type. For example, TPU is very resistant to abrasion and tear-proof. Furthermore, EVA distinguishes itself by having high stability and relatively good cushioning characteristics.
Further, the use of expanded materials was taken into consideration for manufacturing a shoe sole. Expanded thermoplastic polyurethane (eTPU) is known in particular from WO 2008/087078, WO 2007/082838, WO 2010/136398 and WO 2005/066250. Expanded thermoplastic polyurethane distinguishes itself through low weight and particularly good elasticity and cushioning characteristics. Furthermore, according to WO 2005/066250, a sole made of expanded thermoplastic polyurethane may be affixed to a shoe upper without additional adhesive agents.
EP 1 854 620 A1 teaches a method for filling cavities with foam particles. DE 20 2008 017 042 U1 discloses a shaping tool for the manufacture of foamed components made from particles of a synthetic material with a partially closed surface. DE 42 36 081 A1 describes a method for the manufacture of components from foamed synthetic materials and a mold for performing such a method. DE 196 52 690 A1 describes a component, method for the manufacture and apparatus for performing the method. DE 20 2010 008 893 U1 discloses an apparatus for the manufacture of a particle foam component.
For the manufacture of particles from expanded thermoplastic urethane, thermoplastic urethane is for example first of all loaded with a foaming agent in a suspension process or an extrusion process, which then leads to a foaming of the thermoplastic urethane. For example, thermoplastic urethane may initially be stored in water, so that water is absorbed by the thermoplastic urethane, which is evaporated in a further step in order to obtain expanded thermoplastic urethane.
It is known from the prior art to produce different components for the manufacture of soles for shoes, for example, midsole parts out of EVA, torsion elements out of TPU, outsoles out of rubber, viscous cushioning elements out of modified EVA, etc., which are then assembled into a shoe sole in a further manufacturing step.
A disadvantage of the manufacturing methods known from the prior art is that these contain the manufacture of different individual parts of the cushioning element, as just described, which subsequently need to be connected to each other. This means a considerable additional expenditure, since for example different molds are used for manufacturing the individual parts, the individual parts respectively need to be released from these molds and inserted into new molds and the possibilities of exerting influence upon the characteristics of the cushioning elements during the manufacturing process are generally limited.
On the basis of the prior art, it is thus an object of the present invention to provide improved manufacturing methods for cushioning elements for sports apparel. In particular, it is an object of the present invention to provide manufacturing methods for cushioning elements for sports apparel that increase the possibilities of exerting influence upon the characteristics of the cushioning element during its manufacturing process, to reduce the number of manufacturing steps and to simplify the manufacturing process and enable a largely automated manufacture.